Thermoplastic resin compositions suitable for use in transparent laminates
View Patent ↗The present invention is an improved polymeric resin composition comprising or consisting essentially of from about 70 wt % to about 79 wt % units derived from ethylene and from about 21 wt % to about 30 wt % units derived from an α,β-unsaturated carboxylic acid having from 3 to 8 carbons. Resins of the present invention are particularly suitable for preparing transparent laminates useful as glazing elements that provide a greater measure of safety than non-laminated glazing elements. Laminates of the present invention have 3% haze or less without the addition of amines.
1. A process for preparing a transparent laminate article comprising an interlayer sheet, the process comprising the steps of:
(a) extruding a thermoplastic resin at a temperature of from 175° C. to 250° C. to obtain said interlayer sheet, wherein (i) the thermoplastic resin consists essentially of copolymerized units of ethylene and from 20 to 23 wt % of copolymerized units of a carboxylic acid monomer selected from acrylic acid or methacrylic acid, wherein 20% to 35% of the acid groups are neutralized; and the thermoplastic resin has a melt index of about 60 g/10 min or less prior to neutralization; and (iii) the interlayer sheet has a moisture level of 0.066 wt % or less; and b) fabricating a laminate from the interlayer sheet by (1) setting up the interlayer sheet and at least one other laminate layer to form a pre-laminate assembly and (2) heating the pre-laminate assembly to a temperature of at least 120° C. and applying pressure or vacuum to the assembly for a period of time to form a laminate assembly and (3) cooling the laminate temperature to a temperature of 40° C. at a rate of less than 1.0° C./min to obtain the transparent laminate article; wherein the transparent laminate article has a haze of 3% or less and a peel strength is from 16 to 47 lbs/inch when measured at an angle of 90° and at a peel rate of 1 inch/min; and further wherein said interlayer sheet has an adhesion to glass of at least 200 J/m 2 , when measured by Double-Cantilever Beam testing; and said interlayer sheet has an impact toughness of at least 300 kJ/m 2 , when measured according to ASTM 1822.
2. The process of claim 1 , wherein the pre-laminate assembly is heated to a temperature of at least about 130° C.
3. The process of claim 1 , wherein the interlayer sheet has a thickness of from about 0.38 to about 2.60 mm.